In May, Marcus Nagayama, a resident of Minato Ward, allegedly shipped 1 kilogram of kakuseizai, or stimulant drugs, through the mail from the U.S. Valued at 64 million yen, the contraband was hidden in a computer case.

Nagayama, who has been accused of smuggling, denies the charges.

In the same case, police arrested Kazuaki Shirai (39) and Ihho Hatanaka (26) in May. The following month, police accused popular music producer Keisuke Tsukimitsu, 65, of using stimulant drugs at his residence in the Daikanyama area of Shibuya Ward at some point over the last half of May.

Shirai, Hatanaka and Nagayama are believed to be members of a smuggling ring, police said. Tsukimitsu became a target of the investigation when the package containing the contraband was forwarded to his residence after it could not be delivered to the residence of Shirai, located in Meguro Ward.